A NiCoO-Au composite was fabricated following the calcination-reduction method and testified to exhibit the intrinsic high peroxidase- and oxidase-like activities. The composite could activate a low level of HO (100 μM) to kill E. coli and S. aureus. NiCoO-Au composite could be easily separated by an external magnet from the media and reused several times. NiCoO-Au composite could also effectively damage the existing biofilms and prevent the formation of new biofilms. The electron spin resonance tests showed that NiCoO-Au composite catalyzed HO into reactive oxygen species (ROS), mainly including OH, O, and O; while the oxidase-like activity of NiCoO-Au also stemmed from the ROS formation in the absence of HO. The radical trapping experiment confirmed that OH and O were the main radicals in the antibacterial process for NiCoO-Au in the presence of HO. A NiCoO-Au based Band-Aid was also designed, which exhibited high anti-infective and wound-healing properties. This study has demonstrated that NiCoO-Au composite can be a promising antibacterial agent in environmental and clinical applications.